With more and more popularity of smart phones, people's requirements for smart phones are also more and more high, and especially the information security of mobile phones is paid much more attention. System developers and equipment manufacturers are also trying to strengthen the security of phones from various aspects. Google, the developer of Android smart phone system, introduced the system image integrity check function in the latest version, and that function ensures that the phone is not maliciously tampered by attackers through the way that integrity check is performed on the system image at each boot, but the mechanism is not compatible with the OTA upgrading mechanism widely used in the current Android system. Specifically, the OTA upgrading mechanism currently widely used in the Android smart platform is shown in FIG. 1. The upgrading way calculates corresponding differential data by comparing differences in corresponding files in the system in the production process, and packages the data into an OTA upgrading package; and then upgrades the corresponding files in the system to the new version through the upgrading package in the mobile phone side, to achieve the purpose of upgrading the entire system.
The problem of the mechanism, however, is that, although the contents of the upgraded system files are consistent with the new version, the modification order and manner differ for respective specific files in the upgrading process, resulting in that, in a system-level perspective, metadata in the file system has been modified. As a result, when that way works together with the Android system integrity check, it will lead to the failure of the system image check after the upgrading. Therefore, how to achieve the OTA upgrading and also to be compatible with the system image check mechanism has become a technical problem that needs to be solved urgently.